Wjolcz Posted June 8, 2018 Share Posted June 8, 2018 (edited) 2 hours ago, Nibb31 said: They are not going to be spinning the BFS, so yeah, more like Skylab but with a 50% larger diameter. Why not? There are advantages to spinning a spacecraft. Apollo did that to not overheat and astronauts would be able to sleep and do their nasty human toilet stuff relatively comfortably. Edited June 8, 2018 by Wjolcz Quote Link to comment Share on other sites More sharing options...
DAL59 Posted June 8, 2018 Share Posted June 8, 2018 3 hours ago, NSEP said: Its probably going to be less 2001 and more Skylab They should have used Skylab as a habitat for a Mars mission. Quote Link to comment Share on other sites More sharing options...
NSEP Posted June 8, 2018 Share Posted June 8, 2018 10 minutes ago, DAL59 said: They should have used Skylab as a habitat for a Mars mission. I think they were actually planning to use 'wet habitats' for their Venus/Mars flyby concept. 34 minutes ago, Wjolcz said: Why not? There are advantages to spinning a spacecraft. Apollo did that to not overheat and astronauts would be able to sleep and do their nasty human toilet stuff relatively comfortably. They can spin BFS, yes, but we are not sure yet if they will do it. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted June 8, 2018 Share Posted June 8, 2018 Spoiler 4 hours ago, CatastrophicFailure said: Just don't let them add an option: "Eject passenegers" Quote Link to comment Share on other sites More sharing options...
AVaughan Posted June 8, 2018 Share Posted June 8, 2018 2 hours ago, Wjolcz said: Why not? There are advantages to spinning a spacecraft. Apollo did that to not overheat and astronauts would be able to sleep and do their nasty human toilet stuff relatively comfortably. From memory Apollo's Thermal control roll was 3 revolutions per hour. For BFS, at 4.5m radius that would be all of 0.12 mm/s of acceleration. Maybe enough to be noticeable, but probably not enough to help with toilet type tasks. (If you really want a useful amount of "artificial gravity", then you are probably better off using a cable to couple two BFSs nose to nose. But course corrections whilst coupled could be challenging). Quote Link to comment Share on other sites More sharing options...
tater Posted June 8, 2018 Share Posted June 8, 2018 The physical set for 2001 had the (sort of functioning, to the extent that it could rotate, lol) centrifuge at ~11.5m in diameter. This would fit inside the original ITS concept, but not the current iteration. Quote Link to comment Share on other sites More sharing options...
Wjolcz Posted June 8, 2018 Share Posted June 8, 2018 (edited) 10 minutes ago, AVaughan said: From memory Apollo's Thermal control roll was 3 revolutions per hour. For BFS, at 4.5m radius that would be all of 0.12 mm/s of acceleration. Maybe enough to be noticeable, but probably not enough to help with toilet type tasks. (If you really want a useful amount of "artificial gravity", then you are probably better off using a cable to couple two BFSs nose to nose. But course corrections whilst coupled could be challenging). They could probably spin it faster. Not like it would fall apart. And even 1/10 of Earth's gravity wouldn't be bad. I'm not sure how will they keep solar cells aligned. There could be an arm with foldable solar panels that keeps facing the sun or batteries, or maybe even RTG. Edited June 8, 2018 by Wjolcz Quote Link to comment Share on other sites More sharing options...
sh1pman Posted June 8, 2018 Share Posted June 8, 2018 10 minutes ago, Wjolcz said: They could probably spin it faster. Not like it would fall apart. And even 1/10 of Earth's gravity wouldn't be bad. I'm not sure how will they keep solar cells aligned. There could be an arm with foldable solar panels that keeps facing the sun or batteries, or maybe even RTG. Orient the ship radial or antiradial to the Sun? Quote Link to comment Share on other sites More sharing options...
AVaughan Posted June 8, 2018 Share Posted June 8, 2018 Yeah well 5 rpm gets you about 0.12g, but I don't see that fast a rotation rate working with the windows in each sleeping cabin. (I pretty sure that would make me so dizzy that the only alternative would be to shutter those windows, making them pointless). Quote Link to comment Share on other sites More sharing options...
Wjolcz Posted June 8, 2018 Share Posted June 8, 2018 2 minutes ago, sh1pman said: Orient the ship radial or antiradial to the Sun? Oh, I'm dumb. I just remembered I thought of that a while ago but forgot about it now. Quote Link to comment Share on other sites More sharing options...
NSEP Posted June 8, 2018 Share Posted June 8, 2018 1 minute ago, AVaughan said: but I don't see that fast a rotation rate working with the windows in each sleeping cabin. Blinds. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted June 8, 2018 Share Posted June 8, 2018 Over 3 RPM is going to be noticeably unpleasant for at least some of the passengers, though it is possible they may be able to acclimatize over time. We don't have long-term studies of the effects of centrifugal gravity. Quote Link to comment Share on other sites More sharing options...
AVaughan Posted June 8, 2018 Share Posted June 8, 2018 2 minutes ago, NSEP said: Blinds. Functionally the same as shuttering them. Why go to the trouble and expense of adding windows in each cabin if most people can't stand the rotating view? Quote Link to comment Share on other sites More sharing options...
Wjolcz Posted June 8, 2018 Share Posted June 8, 2018 They wouldn't have to rotate it all the time. During the sleep time and/or bathroom hours would probably be enough and not noticable enough to puke and feel dizzy. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted June 8, 2018 Share Posted June 8, 2018 8 minutes ago, Wjolcz said: They wouldn't have to rotate it all the time. During the sleep time and/or bathroom hours would probably be enough and not noticable enough to puke and feel dizzy. If they are going to rotate and un-rotate, they'd either need to pack a yyyyyyuge reaction wheel, or burn a lot of RCS fuel. Quote Link to comment Share on other sites More sharing options...
AVaughan Posted June 8, 2018 Share Posted June 8, 2018 So you waste quite a bit of fuel spinning up and down every few hours? If you were going to do , you would do it once, and then leave the ship rotating until the time for the next course correction or other maneuver. Quote Link to comment Share on other sites More sharing options...
tater Posted June 8, 2018 Share Posted June 8, 2018 You'd put the centrifuge where there were no windows. You'd not really spin it up for more than maybe 0.1g in that small diameter, and even that would require some adaptation. The big question is could the crew go in and out of that and not need to re-adapt every time. If it could work, presumably the centrifuge gets some public space, some bathrooms (removing waste seems like it would require stopping the centrifuge), and exercise equipment. Crew would spend X hours a day under limited gravity, and the rest in microgravity. Even if only some of the toilets were under 0.1g, this could be beneficial. I'm thinking that having... intestinal distress, in a zero-g toilet would be pretty awful. Quote Link to comment Share on other sites More sharing options...
AVaughan Posted June 8, 2018 Share Posted June 8, 2018 2 minutes ago, sevenperforce said: yyyyyyuge reaction wheel Would probably be easier to just build the living quarter inside a rotating drum, running on bearings inside the pressure hull, and then spin the drum in one direction and the ship in the other. Then you can just use the drive motor to start/stop the rotation. That only costs electric power + wear and tear on the moving parts. (And a lot of extra mass you have to lift to orbit etc). Quote Link to comment Share on other sites More sharing options...
Nibb31 Posted June 8, 2018 Share Posted June 8, 2018 32 minutes ago, AVaughan said: Would probably be easier to just build the living quarter inside a rotating drum, running on bearings inside the pressure hull, and then spin the drum in one direction and the ship in the other. Then you can just use the drive motor to start/stop the rotation. That only costs electric power + wear and tear on the moving parts. (And a lot of extra mass you have to lift to orbit etc). You would need a counter-rotating weight to prevent torque rotation of the ship each time you start and stop the ring. It's all overly complex and unnecessary. Rotating a 9m ship is pointless. The gravity would be unnoticeable and with your head rotating at a faster speed than your feet, it would be negated by all sorts of side-effects (dizzyness, nausea, etc...). It might be interesting to use a BFS as an experiment, but not for months of transit to Mars. Quote Link to comment Share on other sites More sharing options...
AVaughan Posted June 8, 2018 Share Posted June 8, 2018 7 minutes ago, Nibb31 said: You would need a counter-rotating weight to prevent torque rotation of the ship each time you start and stop the ring. It's all overly complex and unnecessary. Which is why I suggested placing the drum inside the hull and spinning the drum one way and the rest of the ship the other. Note that I wasn't arguing that spacex should do this, just that it would be better/easier than adding a 'yyyyyyuge reaction wheel' that could spin up/spin down the entire ship. Quote Link to comment Share on other sites More sharing options...
NSEP Posted June 8, 2018 Share Posted June 8, 2018 (edited) 1 hour ago, AVaughan said: if most people can't stand the rotating view? Better question: why have windows if there is nothing to see but darkness and occasionally the sun for most at the time? The best option is to just have a shared window for the people who still want to look, or have a bunch of live-cameras and screens instead. 53 minutes ago, AVaughan said: Would probably be easier to just build the living quarter inside a rotating drum, running on bearings inside the pressure hull, and then spin the drum in one direction and the ship in the other. Then you can just use the drive motor to start/stop the rotation. That only costs electric power + wear and tear on the moving parts. (And a lot of extra mass you have to lift to orbit etc). That wouldn't be easy at all. BFS is a spacecraft that has to handle being thrown around during launch and landing, and has to last a long time with minor refurbishment. If the spinning canister gets stuck somehow, an Astronaut would have to make a risky EVA to not only fix the problem, but also to find it. If the problem is unsolvable or too risky, the spaceship has a large amount of useless mass carrying with it that only causes problems. Not to mention the development cost of testing such a system. BFS is designed to be as simple and low-cost as possible for production, having more advanced gizmos and gadgets that only serve one purpose just makes it worse. I think the best option is to just not go for artificial gravity at all, and use the treadmills and zero-g toilets everyone hates instead. Edited June 8, 2018 by NSEP Quote Link to comment Share on other sites More sharing options...
tater Posted June 8, 2018 Share Posted June 8, 2018 Spinning the entire ship is not unprecedented, in fact the opposite. Apollo did this for heat regulation. Would make more sense with a larger diameter, however. 9m is too small. Quote Link to comment Share on other sites More sharing options...
Nibb31 Posted June 8, 2018 Share Posted June 8, 2018 48 minutes ago, AVaughan said: Which is why I suggested placing the drum inside the hull and spinning the drum one way and the rest of the ship the other. What's the point of having the separate drum inside the hull if the rest of the ship is spinning anyway ? Quote Link to comment Share on other sites More sharing options...
Wjolcz Posted June 8, 2018 Share Posted June 8, 2018 (edited) How about the de-spin yoyos space probes use? They could deploy them and just bring them closer or farther whenever they need to spin faster/slower. Not sure how heavy they would have to be. Edited June 8, 2018 by Wjolcz Quote Link to comment Share on other sites More sharing options...
NSEP Posted June 8, 2018 Share Posted June 8, 2018 Just now, Wjolcz said: How about the de-spin yoyos space probes use? They could deploy then and just bring them closer or farther whenever they need to spin faster. Not sure how heavy they would have to be. That doesn't sound like a bad idea to control the spin. Its nothing extremely complicated. Quote Link to comment Share on other sites More sharing options...
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